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      A Delphi study to develop practical diagnostic guidelines for visual stress (pattern-related visual stress) Translated title: Estudio Delphi para el desarrollo de pautas diagnósticas para el estrés visual (estrés visual relacionado con patrones)

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          Abstract

          Purpose

          Visual stress (VS) is characterised by symptoms of visual perceptual distortions and eyestrain when viewing text, symptoms that are alleviated by individually prescribed coloured filters. A recent review supports the existence of VS and its treatment, but noted that controversy remains, in part due to inconsistencies in the diagnosis of the condition. The present paper reviews the diagnostic criteria for VS in the literature and reports a Delphi analysis of the criteria currently used in clinical practice.

          Methods

          Twenty-six eyecare practitioners were invited to participate in a Delphi study. They were selected because they were frequent prescribers of precision tinted lenses. In the first round they were sent a list of the indicators for which there is literature to suggest a relevance in the diagnosis of VS. The practitioners were invited to rank the indicators and add any additional criteria they use in diagnosis. In the second round a revised list was circulated, including items added from the responses in the first round.

          Results

          The respondents included optometrists, orthoptists and opticians. In the first round the response rate was 85%. Ninety-one percent of those who participated in the first round also responded in the second round. Strong indicators in the second round included the symptom of words moving when reading, voluntary use of an overlay for a prolonged period, improved performance of ≥15% with an overlay on the Wilkins Rate of Reading test, and an abnormally high score on the Pattern Glare Test.

          Conclusions

          The strongest diagnostic criteria are combined in a diagnostic tool. This is proposed as a guide for clinical practice and further research.

          Resumen

          Objetivo

          El estrés visual (EV) se caracteriza por síntomas de distorsión perceptual visual y astenopía, que pueden aliviarse mediante filtros coloreados de prescripción individual. Una revisión reciente respalda la existencia de EV y su tratamiento, aunque hay que resaltar que persiste la controversia, debido en parte a las inconsistencias en cuanto a diagnóstico. El presente documento revisa los criterios diagnósticos del EV en la literatura, y reporta un análisis Delphi sobre los criterios utilizados en la actualidad en la práctica clínica.

          Métodos

          Se invitó a participar en un estudio Delphi a veintiséis facultativos. Éstos fueron seleccionados debido a su elevada prescripción de lentes tintadas de precisión. En la primera ronda, se les envió un listado de los indicadores a los que la literatura aporta relevancia para el diagnóstico del EV. Se solicitó a los facultativos que clasificaran los indicadores, y que añadieran cualquier criterio adicional que ellos utilizaran en su diagnóstico. En la segunda ronda, se hizo circular un listado revisado, incluyendo los ítems añadidos a partir de las respuestas de la primera ronda.

          Resultados

          Entre los facultativos participantes se hallaban optometristas, ortoptistas y ópticos. En la primera ronda el índice de respuesta fue del 85%. El 91% de los participantes en la primera ronda aportaron también sus respuestas en la segunda. Los indicadores sólidos en la segunda ronda incluyeron: síntoma de movimiento de las palabras al leer, uso voluntario de filtros durante un periodo prolongado, mejora del desempeño de ≥15% en el índice de la prueba de lectura de Wilkins con el uso de filtros, y puntuación anormalmente elevada en la prueba PatternGlare.

          Conclusiones

          Se combinan los criterios diagnósticos más sólidos en una herramienta diagnóstica. Ello se propone como pauta en la práctica clínica y la investigación futura.

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          Most cited references48

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          Sparse coding with an overcomplete basis set: a strategy employed by V1?

          The spatial receptive fields of simple cells in mammalian striate cortex have been reasonably well described physiologically and can be characterized as being localized, oriented, and bandpass, comparable with the basis functions of wavelet transforms. Previously, we have shown that these receptive field properties may be accounted for in terms of a strategy for producing a sparse distribution of output activity in response to natural images. Here, in addition to describing this work in a more expansive fashion, we examine the neurobiological implications of sparse coding. Of particular interest is the case when the code is overcomplete--i.e., when the number of code elements is greater than the effective dimensionality of the input space. Because the basis functions are non-orthogonal and not linearly independent of each other, sparsifying the code will recruit only those basis functions necessary for representing a given input, and so the input-output function will deviate from being purely linear. These deviations from linearity provide a potential explanation for the weak forms of non-linearity observed in the response properties of cortical simple cells, and they further make predictions about the expected interactions among units in response to naturalistic stimuli.
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            A neurological basis for visual discomfort.

            Certain patterns of stripes are judged to be unpleasant to look at. They induce illusions of colour, shape and motion that are sometimes perceived predominantly to one side of fixation. People who suffer frequent headaches tend to report more illusions, and if the pain consistently occurs on the same side of the head the illusions tend to be lateralized. The parameters of the patterns that induce illusions (including their shape, spatial frequency, duty cycle, contrast and cortical representation) closely resemble those that elicit epileptiform electroencephalographic abnormalities in patients with photosensitive epilepsy. The viewing conditions under which such abnormalities are likely to appear are also those under which more illusions are seen.
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              Visual sensitivity, blur and the sources of variability in the amplitude spectra of natural scenes.

              A number of researchers have suggested that in order to understand the response properties of cells in the visual pathway, we must consider the statistical structure of the natural environment. In this paper, we focus on one aspect of that structure, namely, the correlational structure which is described by the amplitude or power spectra of natural scenes. We propose that the principle insight one gains from considering the image spectra is in understanding the relative sensitivity of cells tuned to different spatial frequencies. This study employs a model in which the peak sensitivity is constant as a function of frequency with linear bandwith increasing (i.e., approximately constant in octaves). In such a model, the "response magnitude" (i.e., vector length) of cells increases as a function of their optimal (or central) spatial frequency out to about 20 cyc/deg. The result is a code in which the response to natural scenes, whose amplitude spectra typically fall as 1/f, is roughly constant out to 20 cyc/deg. An important consideration in evaluating this model of sensitivity is the fact that natural scenes show considerable variability in their amplitude spectra, with individual scenes showing falloffs which are often steeper or shallower than 1/f. Using a new measure of image structure (the "rectified contrast spectrum" or "RCS") on a set of calibrated natural images, it is shown that a large part of the variability in the spectra is due to differences in the sparseness of local structure at different scales. That is, an image which is "in focus" will have structure (e.g., edges) which has roughly the same magnitude across scale. That is, the loss of high frequency energy in some images is due to the reduction of the number of regions that contain structure rather than the amplitude of that structure. An "in focus" image will have structure (e.g., edges) across scale that have roughly equal magnitude but may vary in the area covered by structure. The slope of the RCS was found to provide a reasonable prediction of physical blur across a variety of scenes in spite of the variability in their amplitude spectra. It was also found to produce a good prediction of perceived blur as judged by human subjects.
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                Author and article information

                Contributors
                Journal
                J Optom
                J Optom
                Journal of Optometry
                Elsevier
                1888-4296
                1989-1342
                24 November 2016
                Jul-Sep 2017
                24 November 2016
                : 10
                : 3
                : 161-168
                Affiliations
                [a ]Institute of Optometry, London, UK
                [b ]Division of Optometry & Visual Science, City, University London, UK
                [c ]Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK
                [d ]University of Essex, Department of Psychology, Colchester, UK
                Author notes
                [* ]Corresponding author at: Institute of Optometry, 56-62 Newington Causeway, London SE1 6DS, UK.Institute of Optometry56-62 Newington CausewayLondonSE1 6DSUK admin@ 123456ioo.org.uk
                Article
                S1888-4296(16)30056-5
                10.1016/j.optom.2016.08.002
                5484780
                27890547
                bb32f521-7628-48a2-b7de-69984102d0ca
                © 2016 Spanish General Council of Optometry. Published by Elsevier Espa˜na, S.L.U.

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                : 8 April 2016
                : 28 August 2016
                Categories
                Original Article

                delphi study,visual stress,pattern-related visual stress,reading,estudio delphi,estrés visual,estrés visual relacionado con patrones,lectura

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